Dehydrator apparatus



6 Sheets-Sheet l INVENTOR, ERV/N H: GUTH/ER.

ATTORNEK E; H. GUTHIER DEHYDRATER APPARATUS Aug. 31, 1948.

Filed Oct. 25, 1945' Aug. 31, 1948.

E. H. GUTHIER DEHYDRATER APPARATUS Filed Oct. 25, 1945 6 Sheets-Sheet 2 ERVIN H. GUT'HIER.

A TTORNEY.

Aug. 31, 1948. E. H. GUTHIER ,4

DEHYDRATER APPARATUS Filed Oct. 25, 1943 s Sheets-Sheet 3 Aug. 31, 1948. E. H'. GUTHIER 2,448,144

DEHYDRATER APPARATUS 6 Sheets-Sheet 4 Filed Oct. 25, 1943- INVENTOR,

m I w H m m A 7' TORNE K Aug. 31, 1948. E. H. GUTHIER 2,448,144

DEHYDRATER APPARATUS I Filed Oct. 25, 1943 6 Sheets-Sheet 6 INVENTORT A v ERV/N H. GUTH/ER.

ATTORNEY.

Patented Aug. 31, 1948 UNITED STATES PATENT OFFICE 2,448,144 V a DEHYDRATOR APPARATUS Ervin H. Guthier, Santa Ana, Calif. Application October 25, 1943, Serial No.'507,525

6 Claims. 1

The present invention relates to improvements in adehydrator apparatus of the tunnel type, and more particularly to a dehydrator apparatus which is adapted for completely automatic operation. 1

Generally, the object of the invention is to improve dehydrators useful in food processing. Further objects are to provide a dehydrator which is equipped with" automatic processing and safety control means, whereby temperature and humidity, and the'like, may be controlled positively and accurately without guesswork on the part of the operator; toprovide'a dehydrator wherein the drying medium, usually heated air, may be circulated or recirculated automatically selectively according tothe' needs of the food being processed as predetermined by the operator; to provide a dehydrator which is adapted for use in handling foods at mass production tempo; to provide a; dehydrator which is designed to eliminate nearly all manual operation by an operator; and to provide dehydration means for food products adapt-ed more completely, efficiently and quickly to dehydrate food products than heretofore has beenpossible. y

Other objects are to provide adehydrator having recirculation and discharge means adapted to be operatediautom atically in accordance with desired conditions'of humidity and temperature; to provide a large capacity dehydrator. which will uniformly dehydrate large volumes of foods; to provide a dehydrator equipped with means adapted. to "channel the drying medium uniformly and completely through the foods being processed before it is discharged or recirculated; to provide a dehydrator which is equipped with door seal means to prevent undesired escape of drying medium;v and toprovide a dehydrator having two tunnelsywherein both tunnels may be used simultaneously to perform two steps indehydrat: ing'foods and the like. i

"Other-objects and advantages will become apparent upon reference to the accompanying specificati'o'n'and drawings hereto annexedand made apart hereof." t a In the drawings similar chara-c'ters of reference'represent"corresponding parts in the several viewsu Fig. 1 is a top plan view of the dehydratori Fig. 2 is -a*side elevatlonal ".view of "the'dehy drator;

Fig. 3 is a front elevational view of thedehydratorr orthe dehydrator.

is an en'd elevati'onal view"of the back Fig. 5 is ,a longitudinal sectional view, taken on the line 5-5 of l.

Fig. 6 is a horizontal sectional view, taken on the line'6-B of Fig. 5.

Fig. 7 is a longitudinal sectional view, taken on the line 1-'--| of Fig. 6.

Fig. 8 is a fragmentary'vertic-al sectional view of a detail of the door construction, as indicated byline 88 of Fig. 4.

Fig. 9 is a transverse sectional view, taken on line 9-9 of Fig. 5.

Fig. 10 is a diagram of the pneumatic controls circuit.

Fig-iris a diagram of the electrical controls circuit. g

The dehydrat'orunit of the tunnel type, preferably heat-insulated throughout, consistsof enclosed dehydrating tunnels, designated generally at 2 and 3, respectively, and a heating tunnel between the two dehydrating tunnels and parallel thereto, designated generally at 4. The heating tunnel comprises three portions, an elevated oven chamberb, a lower chamber 6 (Fig. 5) and a discharge chamber 1. A conventional furnace,

indicated at 8, is positioned below chamber 5, and

a power fan 9, driven by a motor ll through a belt I!) (Fig. 5), is provided in the said heating tunnel chamber 6.

An opening l3 (Fig. 3), positioned above the iurna'ce 8, allows air or'other drying medium to be drawn into the heating tunnel through chamber 6' by the fan. The air is heated by the furnace and discharged by the fan through aperture [4 in partition 15 in the direction of the arrows. Divider member I8 forming two legs of a 'V, the apex of the V being disposed against the back of the dehydrator and the legs veering outwardly therefrom to the drying tunnel walls l2," areprovided to distribute the air discharged by the ran into the drying tunnels. The divider members are fixed in position but are provided with'a plurality of adjustable bafiles l6 controlled by manually operable levers I I, through link members IT, in order to direct the heated air into either or both of the drying tunnels. The air is directed by the divider members to air channeling gate members l9; pivoted at 19 to the point of attachmentnof divider members [8 to Walls I2. ."The members 19 are provided with fixed,

spaced,:vertica-lly disposed vanes 20 (Fig. 6). It will-be noted that the members 19 normally extend ,from'the point of pivotal attachment l9 ang-lularly across thedrying tunnels to the approximate back corners of the drying tunnels, The members are swingable to an open position (see broken lines in Fig. 6) in order to allow easy access to the drying tunnels.

It is noted that the divider members and gate members form a W -shaped, current-directing unit when the gates are in closed position (full lines in Fig. 6). It is pointed out that the outer legs of the W form a more oblique angle with respect to the adjacent V-legs than do the legs of the V per se. The air directing apparatus has proved eminently satisfactory.

The space occupied by the divider and channeling gate members will hereinafter be referred to as the directing chamber.

To afford physical access to the interior of the dehydrator counterbalanced, vertically movable doors, generally indicated at 2!, are provided at each end of each drying tunnel Fig. Bshows a fragmentary sectional view of a door, consisting of two portions, an upper sliding sash 22 and a lower sliding sash 23. The sashes are movable Vertically in guideways 2d and 2 Sash 23 is connected to a sash-cord or cable 25 which leads to a pulley 23 carried by an elevated member 26 supported by braces 2'! and guideway stanchions 27 The sash-cord is connected to a counterbalancing weight 28 (Figs. 4 and 9). A handle 29 is provided on each door in order to allow manual movement thereof. A stop 38 is provided inthe guide passage 2 3 to limit the downward movement of the upper sliding sash 22. Sash 22 is also preferably counterbalanced (not shown) in the-same manner as sash 23 in order to facilitate movement thereof.

On the bottomof the'upper sash 22 I provide an upwardly projecting, metallic strip 3| which is bent slightly angularly outwardly from the side of the sash 22 toward sash 23. A- corresponding downwardly formed strip 32 is provided at the top of sash 23 and which is adapted to nest in strip 31, substantially asshown in Fig; 8, when the sashes are in closed position. A catch 33 is provided on the bottom of sash 23 which projects into guideway 24 to engage the bottom of sash 22 and carry said sash upwardly as saidsash 23 is raised and maintain sash 22in an elevated position. This simplexbutv effective door and, seal connection. prevents escape-of drying medium from the dehydrating tunnels.

The food to .be processed ispreferably. carried by. aplurality of superposed, vertically spaced mesh bottom'trays'35 which are, in turn, carried by wheeled dolliesSB, or other suitable carriers (Fi 9).

The recirculation and discharge means will now be described; At the front or furnace end of each drying tunnel, adjacent to the front door thereof, there is provided an opening 4!! in the. roofs of said tunnels leading to an auxiliary chamber, generally indicated: at M. I provide a recirculation damper 42 in the wall separating the auxiliary chamber 4| from oven chamber 6 and a dischargedamper 43in the roof of chamber communicating with a chimney escape M. The dampers are automatic, selectively and synchronously controlledby means which willshortly be described. As shown in Fig. '7, the recirculation:

damper, allowing communication from the dehy drating tunnels to the heating tunnel, is'open', whilst discharge damper 43 is correspondingly closed. The recirculation and discharge dampers are interconnected (Fig. in such a way that as a recirculation damper is-opened, therelated discharge damper is synchronously closed and vice versa.

From an inspection ofthe drawings it will "be seen that air discharged through the directing chamber into the drying tunnels passes through the foods carried on trays 35 the full length of the drying tunnels to the front thereof where the air currents are then directed upwardly through opening 48 and thence either through recirculation dampers 32 to be reheated and recirculated, or through discharge dampers 43. For example, in Figs. 5 and '7 arrows A indicate the air being passed into recirculation and arrows B represent the air currents which pass through discharge damper 43.

It is very important in drying fod products to controlpositively, accurately and uniformly the moisture content of the air or other drying medium utilized. Some foods react more favorably to a higher moisture content in the air utilized in the drying process than do others. By recirculating air which has been in contact with the foods being processed, a higher moisture content in the drying medium is obtained. On the other-hand, if it is desired to reduce the moisture content of the drying'mediuim, the recirculation dampers are closedyor partially closed, and discharge dampers are opened, or partially opened, so that thea'ir utilized in the drying tunnels or a portion thereof is the comparatively 'dry' air brought in through opening. l3 and heated by the furnace.

By providing openingrdil'at the very front of the enclosed drying tunnels in the roofs thereof, the dryingmedium must pass the entire distance of thelieating tunnel through the foods before it can escape either to the atmosphere or into recirculation. By means of the enclosed tunnels and arrangement of divider members it and channeling members 59 and, to some extent, the superposed, vertically spaced food trays, together withtheposition of the escape-opening 30, the drying: medium thoroughly and uniformly contactsallof the foods being processed without creatingeddies and'undesirable cross currents during itsicompletepassage through a tunnel. This is. amostid'esirable andiadvantageous feature of this invention.

I have provided an adjustable louver grill 65 in the walls ofxchamber 5 above the position of the faniintakegi substantially as indicated in Fig. 5. The purpose of'the airiintake grill 65 is to eliminate-theturbulence andeddy currents caused by the air'entering the inlets of the fan as through chamber 6.. If the said adjustable intake 65 was not available, the airentering the fan from chamber E5 wouldbe subjected'to turbulence adjacent to the partition?! 55. Intake 65 eliminates the possibility of turbulence byallowing a certain amount ofregulated outside air'to flow directly to the fan to mix with the heated air from furnace chamber 6; The auxiliary intake 65 is a very important feature and greatly betters air flow conditions both to'and from the fan.

Fig. 3 shows a View of the exterior of the front of the dehydrator unit, wherein the burner for the furnace is indicated at Ed. The pilot flame fuel conduitis indicated at 5l. A plurality of furnace dampers 52 is provided, together with anumberx of accessories and safety devices, such as gauges, controls" and associated mechanism, which will be more fully described in connection with Figs. 10 and 11.

Fig. eishows the back of the dehydrator adjacent to the directing chamber. A recording con troller. hydrometer and thermostatic control, generally indicated at Bil and which may be set at any predetermined point of desired moisture content and temperature control, is adapted to through wet and. dry bulbthermometer units 61 and62' positioned. in the directing chamber, as

Willlbemore fully described in connectionwith- Fig; 10..

In drying. food products, it is sometimes desirable topassthe foodstuffs through the drying tunnels parallel to the current of. drying medium and then counter to the current of. drying me dium, or vice .versa. My'dehydrator-is adaptable for thispurposeby first passing the foods in the trays,.- for example, through. tunnel 2' with or parallel to the flow of current, as indicated by current arrows in- Fig. 6', and: then removing the said foods from tunnel 2 and passing it through tunnel 3". against. or. counter tothe flowoi the drying medium, as. indicated by. the current arrows in Fig. 2:. In this way'a more thorough and efiicient dryingof the foods may be accomplished.

I have further provided, by means of the adjustable baiiles in divider membersv iii, a way of closing-.offi accessof. drying. medium toone tunnel whilemaintaining the flow-f drying medium to the other'tunnel. In this manner a relatively small volume off-foodstuffs may be handled in a more emcient. and: fuel-saving way than if both tunnels were operatingbut only one of which could handle. the" volume offoods being processed.

Diagrammatic Fig. will now be discussed. The; master controller, generallyindicated at 69., is provided with wet: and drybulb thermometer units. 6!; and 2, whic-h are suitably connected to the controller andmountedorr a panel positioned within the dehydrator; as' at m (Fig. 6); The controller automatically-records and controls the temperature within-the dehydratonas well' asthe moisture content of the drying medium.

Air under-pressure, from a suitable source conveyed through a pneumatic conduitinlet 45 to the controller 60. The conduit is provided with a conventional regulator valve 16,,an air filter H, and shut-off valves 18 and 1.9;. The control mechanism within the controller is adapted to be set at:a predetermined point of moisture content and temperature control, as desired'by the operator' or dictates of circumstance or conditions of operation.

When the moisture content of the drying medium. as recorded by the wet bulb unit, exceeds or isless thanv the desired predetermined point, the controller apparatus actuates. a valve 80, thereby putting pneumatic pressure into line B! which leads to a diverter valve 82 which is connected to branch lines 83. and 8d and a humidifier valve 35, provided with a diaphragm. which controls a humidifier in chamber 5, such as a steam nozzle shown at 81 in Fig. 5. It may be noted that a manual control not shown) maybe employed to cut off communication to either of the lines 83 or 8d, as desired. The air pressure in lines 33 and 34 is conveyed to a diverter switch as and from there, through a line 9 I, to a damper relay mechanism in the damper motor apparatus e2 which allows the main air supply, through conduit 93 and branch conduits 9 5, to operate theipneumatic damper motor 92, which, in turn,

actuates, through appropriate linkage $5, the

pivotally mounted baflles 96 in recirculation,

dampers s2 and discharge dampers 43;

It is noted that the dampers 43 and 6-2 are appropriately connected by linkage, generally indicated at 92', so that as the recirculation damper battles are being closed the discharge dampers are synchronously being opened, and vice versa. The

sourceconduit 93 is connected toany suitablesupply ofv air under pressure.

Ifcth dryingmediumin the dehydrator is extremely dry and not enough moisture is addedto the'air by means-of recirculation thereof, the controller, set at a predetermined point of desired moisture content, allows pneumatic pressure through linealto keep the recirculation dampers open and the dischargedampers closed and simultaneously exertssufficient pressure against the diaphragm of humidifier valve to actuate the said valve and, in turn, actuate the humidifier'll'l in order to supplement the moisture in the dryingmedium to bring the humidity thereof unto-the desired controller setting. On the other hand, if: the moisture-content in the dehydrator is abovethe predetermined controller setting,

the valve to is opened and pneumatic pressure actuates thedamper motor, closing or partially closing the recirculation dampers and correspondinglyopening the discharge dampers untilsuch time-as the balance point, that is, the controller setting point, is reached. In this way the humidity of the drying medium is kept automatically at a constant point by synchronous movement of the discharge and recirculation dampers and the supplemental effect of humid-ifier 81'.

As a safeguard, an auxiliary manual remote rheostaticcontrol switch I0!) is provided to control the damper motors in the event the automatic or controller circuit is out of repair. The manualciricuit is opened through the switch Hill, allowing air-unde-r pressure in line 93, connected to-a suitable source of air under pressure, access to switch H10 and thence through diverter valve 85, through line 9| to actuate the relay mechanism and allow working pressure in line 94 to operate the damper motor. The damper motor operates the recirculation and discharge dampem as desired, by manual rheostatic control of the said switch I00 in the same manner as when operated automatically by the controller 60.

Pressure'gauges "H are provided on several of the lines in order to keep an accurate check on the pressure in the various conduits.

The controllerfifl records and controls the thermostatic conditions within the dehydrator through the medium of the dry bulb unit 62. The desired temperature within the dehydrator may be'controlled at a predetermined point by means of adjustment of the controller, as in the case of humidity, and when the temperature in the said dehydrator. falls below or climbs above the point of'setting, a valve Hi5, similar to the valve 80, already referred to, is opened, allowing pneumatic pressure access to line H I and thence to. an electric pneumatic valve H2 to a gas valve I 13 which controls the gas burner of the furnace. valve H2 is connected to electrical lead lines C leading. to -the electrical control circuit, generally indicated at D..

For example, if the air or drying medium temperature in the dehydrator is less than the controller point, valve H0 is automatically opened, actuating the gas valve, allowing additionalgas. to be utilized in the furnace and thereby raising; the temperature. On the other hand, if the temperature v-in' the dehydrator is higher than the controller point, the flow of gas is cut down proportionately in order to lower the temperature.

Diagrarnmatic Fig. 11 shows the electrical hook-up. for the automatic controls utilized in the dehydrator. The flame protection unit I I4 is designed to reduce to a minimum the possibility of explosion. It controls both the pilot flame solenoid valve H5, which controls the flow of gas to the pilot burner (not shown) and the electric pneumatic valve I I2 through the medium of an electrode 1, positioned across the pilot flame (not shown) so that if thelpilot flame is extinguished for any reason the protection unit will close the pilot valve H5, as well as the electric-pneumatic valve to cut off flow of gas to the furnace. It also closes the alarm circuit to operate an alarm bell I I8.

Electric source lead lines I i9 furnish electric power for the various control units through leads shown in the drawings. The flame protection unit has a conventional time delay device (not shown) to allow a period. of time sufficient to purge all gas from the dehydrator from the time the fan motor is started until the pilot valve H opens. The protection unit also controls the pilot flame ignition circuit, generally indicated at IZI and'including transformer I22, and will not allow the electric-pneumatic valve II2 to open to feed gas to the furnace through valve I I3 (Fig. until the pilot flame has been started and is functioning properly;

I also provide an air flow sWltch I23, located in the path of the air stream generated by the fan which is electrically operated. The air flow switch is a conventional apparatus designed to close the alarm circuit when the air current from the fan fails. If the fan motor stops or the fan belt breaks, the air flow stops, thus breaking the electric circuit with the electric-pneumatic valve which, in turn, cuts off gas to the burner. It also closes the alarm circuit to sound the alarm II8.

I also provide a high temperature limit switch I 26, which is simply a thermostatic dry bulb controller electrically operated. It is connected to the electric-pneumatic valve II2. Usually I prefer to set the high temperature switch five degrees to ten degrees above the operating temperature of the wet and dry controller 69, so that if the said controller fails to operate for any reason, the switch I26 will break the electric circuit with the electric-pneumatic valve, thereby shutting off the gas supply to the furnace.

A dual push-button switch I21 is provided in the control circuit for two consecutive safety operations. When the button is pushed in, contact is made with the high voltage transformer I22, and electric ignition through [2| is provided to light the pilot flame 5i, and, if a successful lighting of the pilot flame is accomplished a visual signal light in the flame protection unit H4 is extinguished. When the push-button is released to its normal position, after a successful ignition operation, it opens the electric-pneumatic valve I I2, thus supplying air pressure to the gas valve H3, Which, in turn, opens gas valve II3. If the electric ignition operation is not successful, when pushing the button in, then the visual signal l ght will not be extinguished and the electric-pneumatic valve IIZ will not open when the push-button is released to its normal position.

It will be noted that if any of theabove circuits connected into the electric-pneumatic valve IIZ are opened, the pneumatic pressure therethrough to the gas valve H3 (Fig. 10) is shut ofi, thereby cutting on" the supply of gas to the burner.

The units comprising my control system are all conventional apparatus available on the open market. The novel and useful arrangement of such units as applied to my dehydrating apparatus, as herein described and illustrated, make it possible to process foods in a manner reduced to scientific accuracy. A better quality food product is obtained with much less labor and operating costs than hereto-fore known and with a greater degree of safety. Large volumes of food products may be easily and efficiently processed at mass production tempo.

While I have described my apparatus in more or less detail of embodiment, it is understood that various modifications and alterations may be made within the spirit of the invention and the scope of the appended claims.

I claim:

1. A dehydrating apparatus comprising a plurality of enclosed drying tunnels, a heating tunnel, means to heat a drying medium in said heating tunnel, means to impart circulatory movement to said drying medium, a directing chamber at one end of said apparatus in flow communication with said drying tunnels and said heating tunnels, fixed divider members having adjustable baiiles positioned in said directing chamber, said divider members adapted to direct drying medium issuing from the heating tunnel to said drying tunnels, movable channeling members having fixed baffles positioned in said chamber each of said channeling members movable across the intake end of a drying tunnel, each of said divider members adaptable to close off communication between said heating tunnel and a drying tunnel, and means to recirculate and discharge selectively and synchronously said drying medium, said last mentioned means positioned in said tunnels adjacent the ends thereof opposite to said directing chamber and comprising automatically controlled damper units acting in synchronized movement with respect to one another.

2. A dehydrating apparatus comprising a plurality of enclosed drying tunnels, a heating tunnel, means to heat a drying medium in said heating tunnel, means to impart circulatory movement to said drying medium, a directing chamber at one end of said apparatus in flow communication with said heating tunnel and said drying tunnels, fixed divider members having adjustable baflies positioned in said directing chamber, movable channeling members having fixed baffles positioned in said chamber, said divider members disposed in the shape of a V, the apex of said V being positioned adjacent the end Wall of said directing chamber, each of said channeling members pivoted adjacent an end of a said divider member and swingable across a drying tunnel, and means to recirculate and discharge selectively said drying medium comprising automatically controlled damper units actin in synchronized movement with respect to one another.

3. A dehydrating apparatus comprising a plurality of enclosed drying tunnels, a heating tunnel, means to heat a drying medium in said heating tunnel, means to impart circulatory movement to said drying medium, a directing chamber at one end of said apparatus in flow communication with said heating tunnel and said drying tunnels, discharge conduits in flow communication with said drying tunnels adjacent to the ends thereof opposite to said directing chamber, divider members in said directing chamber disposed in the shape of a V, the apex of said V being positioned adjacent the end wall of said chamber and the legs of said V veering outwardly from said wall toward said heating tunnel, channeling members pivoted adjacent the ends of said divider members and swingable across said drying tunnels whereby said divider members and channeling members form a W- shaped directing apparatus when said channeling members are moved across said tunnels, adjustable bafiles in said divider members, and fixed spaced vertically disposed baffles in said channeling members, said baille members adapted to control the flow of drying medium issuing from said heating tunnel into said drying tunnels.

4. A dehydratin apparatus comprising a p111- rality of enclosed drying tunnels, a heating tunnel, means to heat a drying medium in said heating tunnel, means to impart circulatory movement to said drying medium, a directing chamber at one end of said apparatus in flow communication with said drying tunnels and said heating tunnel, fixed divider members having adjustable baffles positioned in said directing chamber, said divider members adapted to direct drying medium issuing from the heating tunnel to said drying tunnels, movable channelling members having fixed bailies positioned in said chamber, each of said channelling members movable across the intake end of a drying tunnel, each of said divider members adaptable to close ofi communication between said heating tunnel and a drying tunnel, means to recirculate and discharge selectively and synchronously said drying medium, said last mentioned means positioned in said tunnels adjacent to the ends thereof opposite to said directing chamber and comprising automatically controlled damper units acting in synchronized movement with respect to one another, and auxiliary air inlet means positioned adjacent to said circulatory means to allow unheated air access to said circulatory means.

5. A dehydrating apparatus comprising a plurality of enclosed drying tunnels, a heating tunnel, means to heat a drying medium in said heating tunnel, means to impart circulatory movement to said drying medium, a directing chamber at one end of said apparatus in flow communication with said heating tunnel and said drying tunnels, fixed divider members having adjustable bafiies positioned in said directing chamber, movable channelling members having fixed baffies positioned in said chamber, said divider members disposed in the shape of a V, the apex of said V being positioned adjacent to the end wall of said directing chamber, each of said channelling members pivoted adjacent to an end of a said divider member and s-wingable across a drying tunnel, means to recirculate and discharge selectively said drying medium comprising automatically controlled damper units acting in synchronized movement with respect to one another, and auxiliary air inlet means positioned adjacent to said circulatory means to allow unheated air access to said circulatory means.

6. A dehydrating apparatus comprising a heating tunnel, a main air inlet provided in the forward end of said heating tunnel, a drying tunnel, a heating unit in said heating tunnel to heat a drying medium, means in said heating tunnel to impart a circulatory movement to said drying medium, means to direct said drying medium from the heating tunnel to the drying tunnel, a chamber positioned above said drying tunnel and in flow communication therewith, means defining a port providing communication between said chamber and said heating tunnel, a recirculation damper in said port to close off communication between said drying tunnel and said heating tunnel through said chamber, a discharge port and damper in said chamber adjacent to said recirculation damper, and auxiliary air inlet means provided in said heating tunnel and spaced rearwardly from said main air inlet and positioned adjacent to the drying medium inlet opening of said circulatory means to allow unheated air entering said heating tunnel through said auxiliary air inlet means direct access to said circulatory means to mix with heated air circulated by said circulatory means.

ERVIN H. GUTHIER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,431,145 Bolling Oct. 10, 1922 1,512,741 Barr Oct. 21, 1924 1,550,422 Braemer Aug. 18, 1925 1,554,914 Guthier Sept. 22, 1925 1,624,639 'Thomasen Apr. 12, 1927 1,805,173 Griffoul May 12, 1931 2,040,328 Olson May 12, 1936 2,156,295 Kiesling May 2, 1939 2,190,349 Beam Feb. 13, 1940 2,223,696 Mayo Dec. 3, 1940 2,237,248 Denison Apr. 1, 1941 2,238,318 Goecke Apr. 15, 1941 2,254,621 Moore Sept. 2, 1941 2,294,780 Pfenning Sept. 1, 1942 2,297,318 Parkes Sept. 29, 1942 2,312,479 Ray Mar. 2, 1943 2,318,027 Sykes et al. May 4, 1943 2.351.487 Cooney June 13, 1944 

